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Im C, Seo W, Park S, Kim K, Park S, Choo H. Design of a Deployable Broadband Mesh Reflector Antenna for a SIGINT Satellite System Considering Surface Shape Deformation. Sensors (Basel) 2024; 24:384. [PMID: 38257477 PMCID: PMC10819937 DOI: 10.3390/s24020384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2023] [Revised: 01/05/2024] [Accepted: 01/06/2024] [Indexed: 01/24/2024]
Abstract
In this paper, we propose a deployable broadband mesh reflector antenna for use in signals intelligence (SIGINT) satellite systems, considering performance degradation due to shape deformation. To maximize gain by increasing the diameter of the reflector while reducing the weight of the antenna, the reflector of the antenna is designed using lightweight silver-coated Teflon mesh. The mesh reflectors are typically expanded by tension to maintain their parabolic structure; thus, shape deformation cannot be avoided. This shape deformation results in shape differences between the surface of the mesh reflector and the ideal parabolic reflector, thus resulting in the degradation of the performance of the mesh reflector antenna. To observe this degradation, we analyze antenna performance according to the number of arms, the number of joints, the feed distance, and the distance from the reflector center to each joint. The performance of the mesh reflector antenna is examined using an effective lossy conducting surface (ELCS) that has the same reflectivity as the silver-coated Teflon mesh to reduce simulation time and computing resources. The designed silver-coated Teflon mesh reflector and the double-ridged feed antenna are fabricated, and the bore-sight gain is measured using the three-antenna method. The measured bore-sight gain of the proposed antenna is 31.6 dBi at 10 GHz, and the measured and simulated results show an average difference of 3.28 dB from 2 GHz to 18 GHz. The proposed deployable mesh reflector antenna can be used in a variety of applications where small stowed volume is required for mobility, such as mobile high-gain antennas as well as satellite antenna systems. Through this study, we demonstrate that shape deformation of the mesh reflector surface significantly affects the performance of reflector antennas.
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Affiliation(s)
- Changhyeon Im
- Department of Electronic and Electrical Engineering, Hongik University, Seoul 04066, Republic of Korea;
| | - Wongu Seo
- Hanwha Systems Company Ltd., Seongnam 04541, Republic of Korea; (W.S.); (S.P.); (K.K.); (S.P.)
| | - Seulgi Park
- Hanwha Systems Company Ltd., Seongnam 04541, Republic of Korea; (W.S.); (S.P.); (K.K.); (S.P.)
| | - Kihun Kim
- Hanwha Systems Company Ltd., Seongnam 04541, Republic of Korea; (W.S.); (S.P.); (K.K.); (S.P.)
| | - Sungkyun Park
- Hanwha Systems Company Ltd., Seongnam 04541, Republic of Korea; (W.S.); (S.P.); (K.K.); (S.P.)
| | - Hosung Choo
- Department of Electronic and Electrical Engineering, Hongik University, Seoul 04066, Republic of Korea;
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Youn S, Ohm S, Jang BJ, Choo H. Design of a Tripod-Shaped Radiator Patch Antenna for Ultra-Wideband Direction Finding. Sensors (Basel) 2023; 23:9157. [PMID: 38005544 PMCID: PMC10674202 DOI: 10.3390/s23229157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 11/09/2023] [Accepted: 11/10/2023] [Indexed: 11/26/2023]
Abstract
As UWB technology develops and devices become smaller, miniaturization techniques for an array antenna system are required. In addition, more in-depth research is needed for UWB direction-finding techniques using channel impulse response (CIR) data. This paper proposes an ultra-wideband (UWB) antenna using a single-radiator multiple-port (SRMP) design for the direction-finding systems of smart devices. The proposed SRMP antenna was designed using a single tripod-shaped patch that can replace the array system. The tripod-shaped radiator was optimized using the edge shape design function to improve its broadband and mutual coupling characteristics. For performance verification, the proposed antenna was fabricated, and the reflection coefficient, mutual coupling, and radiation patterns were measured in a fully anechoic chamber. The proposed antenna has an operating frequency band of 6.1 GHz (from 5.8 GHz to 11.9 GHz) for port 1 and a measured mutual coupling of -14.8 dB at 8 GHz. The SRMP antenna has measured maximum gains of 3.5 dBi for port 1 and 2.9 dBi for port 2. To examine the direction-finding performance, the fabricated antenna was connected to a circuit module with a DW3000 chip, which is widely employed in commercial mobile UWB systems. The direction of arrival (DoA) results using the measured CIR data show root-mean-square (RMS) errors of 1.57° and 4.58° at distances of 30 cm and 60 cm.
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Affiliation(s)
- Sangwoon Youn
- Department of Electronic and Electrical Engineering, Hongik University, Seoul 04066, Republic of Korea;
| | - Sungsik Ohm
- Tactical Communication System Team, Hanwha Systems, Seongnam 13524, Republic of Korea;
| | - Byung-Jun Jang
- Department of Electrical Engineering, Kookmin University, Seoul 04066, Republic of Korea;
| | - Hosung Choo
- Department of Electronic and Electrical Engineering, Hongik University, Seoul 04066, Republic of Korea;
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Im C, Lim TH, Choo H. Design of a mmWave Antenna Printed on a Thick Vehicle-Glass Substrate Using a Linearly Arrayed Patch Director and a Grid-Slotted Patch Reflector for High-Gain Characteristics. Sensors (Basel) 2022; 22:6187. [PMID: 36015948 PMCID: PMC9416414 DOI: 10.3390/s22166187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 08/12/2022] [Accepted: 08/15/2022] [Indexed: 06/15/2023]
Abstract
This paper proposes a 5G glass antenna that can be printed on the thick window glass of a vehicle. The proposed antenna consists of a coplanar waveguide (CPW), a printed monopole radiator, parasitic elements, a linearly arrayed patch director, and a grid-slotted patch reflector. The linearly arrayed patch director and grid-slotted patch reflector are applied to improve the bore-sight gain of the antenna. To verify the performance improvement and feasibility, the proposed antenna is fabricated, and a reflection coefficient and a radiation pattern are measured and compared with the simulation results. The measured reflection coefficient shows broadband characteristics of less than -10 dB from 24.1 GHz to 31.0 GHz (fractional bandwidth of 24.6%), which agrees well with the simulation results. The reflection coefficients are -33.1 dB by measurement and -25.7 dB by simulation, and the maximum gains are 6.2 dBi and 5.5 dBi at 28 GHz, respectively. These results demonstrate that the proposed antenna has high-gain characteristics being suitable for 5G wireless communications.
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Affiliation(s)
- Changhyeon Im
- Department of Electronic and Electrical Engineering, Hongik University, Seoul 04066, Korea
| | - Tae Heung Lim
- Department of Electrical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Korea
| | - Hosung Choo
- Department of Electronic and Electrical Engineering, Hongik University, Seoul 04066, Korea
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Kang E, Lim TH, Park S, Choo H. Design of a Novel Wideband Leaf-Shaped Printed Dipole Array Antenna Using a Parasitic Loop for High-Power Jamming Applications. Sensors (Basel) 2021; 21:s21206882. [PMID: 34696100 PMCID: PMC8540365 DOI: 10.3390/s21206882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 10/09/2021] [Accepted: 10/11/2021] [Indexed: 11/16/2022]
Abstract
This paper proposes a novel wideband leaf-shaped printed dipole antenna sensor that uses a parasitic element to improve the impedance matching bandwidth characteristics for high-power jamming applications. The proposed antenna sensor consists of leaf-shaped dipole radiators, matching posts, rectangular slots, and a parasitic loop element. The leaf-shaped dipole radiators are designed with exponential curves to obtain a high directive pattern and are printed on a TLY-5 substrate for high-power durability. The matching posts, rectangular slots, and a parasitic loop element are used to enhance the impedance matching characteristics. The proposed antenna sensor has a measured fractional bandwidth of 66.7% at a center frequency of 4.5 GHz. To confirm the array antenna sensor characteristics, such as its active reflection coefficients (ARCs) and beam steering gains, the proposed single antenna sensor is extended to an 11 × 1 uniform linear array. The average values of the simulated and measured ARCs from 4.5 to 6 GHz are -13.4 dB and -14.7 dB. In addition, the measured bore-sight array gains of the co-polarization are 13.4 dBi and 13.7 dBi at 4 GHz and 5 GHz, while those of the cross-polarizations are -4.9 dBi and -3.4 dBi, respectively. When the beam is steered at a steering angle, θ0, of 15°, the maximum measured array gains of the co-polarization are 12.2 dBi and 10.3 dBi at 4 GHz and 5 GHz, respectively.
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Affiliation(s)
- Eunjung Kang
- Department of Electronic and Electrical Engineering, Hongik University, Seoul 04066, Korea; (E.K.); (H.C.)
| | - Tae Heung Lim
- Department of Electronic and Electrical Engineering, Hongik University, Seoul 04066, Korea; (E.K.); (H.C.)
- Correspondence:
| | - Seulgi Park
- Hanwha Systems Co., Ltd., Seongnam City 13524, Korea;
| | - Hosung Choo
- Department of Electronic and Electrical Engineering, Hongik University, Seoul 04066, Korea; (E.K.); (H.C.)
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Youn S, Lim TH, Kang E, Lee DH, Kim KB, Choo H. Design of a Miniaturized Rectangular Multiturn Loop Antenna for Shielding Effectiveness Measurement. Sensors (Basel) 2020; 20:s20113178. [PMID: 32503279 PMCID: PMC7309120 DOI: 10.3390/s20113178] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Revised: 05/24/2020] [Accepted: 06/02/2020] [Indexed: 11/16/2022]
Abstract
This paper proposes a novel miniaturized rectangular loop antenna sensor consisting of a multiturn wire and a cuboid ferrite core. The lateral surface of the ferrite core is tightly wound by the multiturn wire. To verify its feasibility, the antenna sensor is fabricated, and the antenna factor (AF) levels are measured using the three-antenna method from the very low frequency (VLF) to the high-frequency (HF) bands. The measured AF levels are 31.8 dB (with a covering plastic case) and 33.1 dB (without a covering plastic case) at 30 kHz. In addition, the proposed antenna is employed in the shielding effectiveness measurement of a small commercial cabinet to observe its suitability for shielding effectiveness (SE) measurement of small shielding enclosures. The SE values averaged over the frequency range from 10 kHz to 3 MHz are 4.1 dB and 12 dB in the horizontal and vertical polarizations, respectively.
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Affiliation(s)
- Sangwoon Youn
- School of Electronic and Electrical Engineering, Hongik University, Seoul 04066, Korea; (S.Y.); (T.H.L.); (E.K.)
| | - Tae Heung Lim
- School of Electronic and Electrical Engineering, Hongik University, Seoul 04066, Korea; (S.Y.); (T.H.L.); (E.K.)
| | - Eunjung Kang
- School of Electronic and Electrical Engineering, Hongik University, Seoul 04066, Korea; (S.Y.); (T.H.L.); (E.K.)
| | - Dae Heon Lee
- Affiliated Institute of Electronics and Telecommunications Research Institute, Daejeon 30147, Korea; (D.H.L.); (K.B.K.)
| | - Ki Baek Kim
- Affiliated Institute of Electronics and Telecommunications Research Institute, Daejeon 30147, Korea; (D.H.L.); (K.B.K.)
| | - Hosung Choo
- School of Electronic and Electrical Engineering, Hongik University, Seoul 04066, Korea; (S.Y.); (T.H.L.); (E.K.)
- Correspondence:
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Jung YS, Paik H, Min SH, Choo H, Seo M, Bahk JH, Seo JH. Calling the patient's own name facilitates recovery from general anaesthesia: a randomised double-blind trial. Anaesthesia 2016; 72:197-203. [DOI: 10.1111/anae.13688] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/24/2016] [Indexed: 11/28/2022]
Affiliation(s)
- Y. S. Jung
- Department of Anaesthesiology and Pain Medicine; Seoul National University Hospital; Seoul Korea
| | - H. Paik
- Department of Anaesthesiology and Pain Medicine; Seoul National University Hospital; Seoul Korea
| | - S.-H. Min
- Department of Anaesthesiology and Pain Medicine; Seoul National University Hospital; Seoul Korea
| | - H. Choo
- Department of Anaesthesiology and Pain Medicine; Seoul National University Hospital; Seoul Korea
| | - M. Seo
- Department of Anaesthesiology and Pain Medicine; Seoul National University Hospital; Seoul Korea
| | - J.-H. Bahk
- Department of Anaesthesiology and Pain Medicine; Seoul National University Hospital; Seoul Korea
- Seoul National University College of Medicine; Seoul Korea
| | - J.-H. Seo
- Department of Anaesthesiology and Pain Medicine; Seoul National University Hospital; Seoul Korea
- Seoul National University College of Medicine; Seoul Korea
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Choo H, Shen D, Walther D. Local Structure Drives Human Scene Categorization: Converging Evidence from Computational Analysis, Behavior, and Neural Decoding. J Vis 2014. [DOI: 10.1167/14.10.1124] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Choo H, Walther D. Disrupting local structure impairs human scene categorization more than disrupting global texture. J Vis 2013. [DOI: 10.1167/13.9.1045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Bao W, Melli M, Caselli N, Riboli F, Wiersma DS, Staffaroni M, Choo H, Ogletree DF, Aloni S, Bokor J, Cabrini S, Intonti F, Salmeron MB, Yablonovitch E, Schuck PJ, Weber-Bargioni A. Mapping Local Charge Recombination Heterogeneity by Multidimensional Nanospectroscopic Imaging. Science 2012; 338:1317-21. [DOI: 10.1126/science.1227977] [Citation(s) in RCA: 127] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Wei Bao
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Department of Materials Science and Engineering, University of California Berkeley, Berkeley, CA 94720, USA
| | - M. Melli
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - N. Caselli
- European Laboratory for Non-Linear Spectroscopy, 50019 Sesto Fiorentino, Firenze, Italy
- Dipartimento di Fisica e Astronomia, Università di Firenze, 50019 Sesto Fiorentino, Firenze, Italy
| | - F. Riboli
- European Laboratory for Non-Linear Spectroscopy, 50019 Sesto Fiorentino, Firenze, Italy
- Dipartimento di Fisica e Astronomia, Università di Firenze, 50019 Sesto Fiorentino, Firenze, Italy
| | - D. S. Wiersma
- European Laboratory for Non-Linear Spectroscopy, 50019 Sesto Fiorentino, Firenze, Italy
- Istituto Nazionale di Ottica (CNR-INO), 50125 Firenze, Italy
| | - M. Staffaroni
- Department of Electrical Engineering and Computer Sciences, University of California Berkeley, Berkeley, CA 94720–1770, USA
| | - H. Choo
- Department of Electrical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - D. F. Ogletree
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - S. Aloni
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - J. Bokor
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Department of Electrical Engineering and Computer Sciences, University of California Berkeley, Berkeley, CA 94720–1770, USA
| | - S. Cabrini
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - F. Intonti
- European Laboratory for Non-Linear Spectroscopy, 50019 Sesto Fiorentino, Firenze, Italy
- Dipartimento di Fisica e Astronomia, Università di Firenze, 50019 Sesto Fiorentino, Firenze, Italy
| | - M. B. Salmeron
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Department of Materials Science and Engineering, University of California Berkeley, Berkeley, CA 94720, USA
| | - E. Yablonovitch
- Department of Electrical Engineering and Computer Sciences, University of California Berkeley, Berkeley, CA 94720–1770, USA
| | - P. J. Schuck
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - A. Weber-Bargioni
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
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Choo H, Franconeri S. Small collections violate Weber's law during relative number judgments. J Vis 2012. [DOI: 10.1167/12.9.509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Choo H, Franconeri S. Relation binding deficits during rapid spatial relationship judgments. J Vis 2011. [DOI: 10.1167/11.11.148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Zayak AT, Hu YS, Choo H, Bokor J, Cabrini S, Schuck PJ, Neaton JB. Chemical Raman enhancement of organic adsorbates on metal surfaces. Phys Rev Lett 2011; 106:083003. [PMID: 21405569 DOI: 10.1103/physrevlett.106.083003] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Indexed: 05/16/2023]
Abstract
Using first-principles theory and experiments, chemical contributions to surface-enhanced Raman spectroscopy for a well-studied organic molecule, benzene thiol, chemisorbed on planar Au(111) surfaces are explained and quantified. Density functional theory calculations of the static Raman tensor demonstrate a strong mode-dependent modification of benzene thiol Raman spectra by Au substrates. Raman active modes with the largest enhancements result from stronger contributions from Au to their electron-vibron coupling, as quantified through a deformation potential. A straightforward and general analysis is introduced to extract chemical enhancement from experiments for specific vibrational modes; measured values are in excellent agreement with our calculations.
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Affiliation(s)
- A T Zayak
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley California 94720, USA
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Choo H, Franconeri S. Perception of average orientation. J Vis 2010. [DOI: 10.1167/9.8.939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Mar DJ, Marsh JP, Deen CP, Ling H, Choo H, Jaffe DT. Micromachined silicon grisms for infrared optics. Appl Opt 2009; 48:1016-1029. [PMID: 23567560 DOI: 10.1364/ao.48.001016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We demonstrate the successful fabrication of large format (approximately 50 mm × 50 mm) gratings in monolithic silicon for use as high-efficiency grisms at infrared wavelengths. The substrates for the grisms were thick (8-16 mm) disks of precisely oriented single-crystal silicon (refractive index, n ~ 3.42). We used microlithography and chemical wet etching techniques to produce the diffraction gratings on one side of these substrates. These techniques permitted the manufacture of coarse grooves (as few as 7 grooves/mm) with precise control of the blaze angle and groove profile and resulted in excellent groove surface quality. Profilometric measurements of the groove structure of the gratings confirm that the physical dimensions of the final devices closely match their design values. Optical performance of these devices exceeds the specifications required for diffraction-limited performance (RMS wave surface error <λ/20) in the near- and mid-infrared (1-40 μm). Peak diffraction efficiencies measured in the reflection range from 70-95% of the theoretical maximum. Tests of our grisms in the near infrared indicate transmission efficiencies of 30-48% uncorrected for Fresnel losses and confirm excellent performance. In infrared wavelength regions where silicon transmits well, the blaze control and high index permit high-resolution, high-order dispersion in a compact space. The first application of these grisms is to provide FORCAST, a mid-infrared camera on NASA's airborne observatory, with a moderate resolution (R=100-1000) spectroscopic capability.
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Affiliation(s)
- Douglas J Mar
- Liquidia Technologies, Inc., North Carolina, USA; Department of Astronomy, The University of Texas at Austin, Austin Texas, USA
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Wang YD, Ren Y, Li H, Cong DY, Choo H, Liaw PK, Peng RL, Zuo L. Measurements of textures and stresses in Ni2MnGa ferromagnetic shape-memory alloys. GNER 2007. [DOI: 10.1080/10238160802399654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Liaw P, Choo H, Buchanan R, Hubbard C, Wang X. International Materials Institutes [IMI], Advanced Neutron Scattering Network for Education and Research [ANSWER]: With a Focus on Mechanical Behavior of Materials. Journal of Neutron Research 2003. [DOI: 10.1080/10238160410001726648] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Loosemore M, Choo H, Koh J. Encouraging Research and Development in Construction Companies. J Prof Issues Eng Educ Pract 2002. [DOI: 10.1061/(asce)1052-3928(2002)128:1(25)] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Affiliation(s)
- M. Loosemore
- Associate Professor, Univ. of New South Wales, Sydney 2052, Australia
| | - H. Choo
- Research Assistant, Univ. of New South Wales, Sydney 2052, Australia
| | - J. Koh
- Univ. of New South Wales, Sydney 2052, Australia
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Song GY, Paul V, Choo H, Morrey J, Sidwell RW, Schinazi RF, Chu CK. Enantiomeric synthesis of D- and L-cyclopentenyl nucleosides and their antiviral activity against HIV and West Nile virus. J Med Chem 2001; 44:3985-93. [PMID: 11689085 DOI: 10.1021/jm010256v] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Enantiomeric synthesis of D- and L-cyclopentenyl nucleosides and their antiviral activity against HIV and West Nile virus are described. The key intermediate (-)- and (+)-cyclopentenyl alcohols (7 and 15) were prepared from D-gamma-ribonolactone and D-ribose, respectively. Coupling of 7 with appropriately blocked purine and pyrimidine bases via the Mitsunobu reaction followed by deprotection afforded the target L-(+)-cyclopentenyl nucleosides (24-28, 31, 33, and 36). D-(-)-Cyclopentenyl nucleosides (1, 40, 43, and 52-56) were also prepared by a similar procedure for L-isomers from 15. The synthesized compounds were evaluated for their antiviral activity against two RNA viruses: HIV and West Nile virus. Among the synthesized D-(-)-nucleosides, adenine (1, neplanocin A), cytosine (55, CPE-C), and 5-fluorocytosine (56) analogues exhibited moderate to potent anti-HIV activity (EC(50) 0.1, 0.06, and 5.34 microM, respectively) with significant cytotoxicity in PBM, Vero, and CEM cells. Also, cytosine (55) and 5-fluorocytosine (56) analogues exhibited the most potent anti-West Nile virus activity (EC(50) 0.2-3.0 and 15-20 microM, respectively). Among L-(+)-nucleosides, only the cytosine (27) analogue exhibited weak anti-HIV activity (EC(50) 58.9 microM).
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Affiliation(s)
- G Y Song
- College of Pharmacy, The University of Georgia, Athens, Georgia 30602, USA
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Abstract
[reaction: see text] Carbocyclic L-2'deoxynucleosides 17 were synthesized on solid phase in four steps from the appropriately protected intermedate 11. The Mitsunobu reaction was used as a condensation method between the carbocyclic moiety and heterocyclic bases. The regioselectivity of the carbocyclic nucleosides was compared between the solid and solution phase syntheses.
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Affiliation(s)
- H Choo
- Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, The University of Georgia, Athens, Georgia 30602-2352, USA
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Abstract
Very early reperfusion after coronary occlusion can reduce infarct size and preserve left ventricular function. Whether later reperfusion is of benefit is unclear. We studied the effect of very early reperfusion with myocardial salvage and "late" reperfusion without myocardial salvage on infarct expansion and aneurysm formation. Sixty-eight rats underwent left coronary artery ligation and were randomized to 30 min reperfusion, 2 hr reperfusion, or permanent coronary artery ligation. The animals were killed and the hearts examined at 2 weeks. Thirty minute reperfusion reduced infarct size, extent of transmurality, and infarct expansion. Two hour reperfusion reduced neither infarct size nor transmurality but inhibited infarct expansion. The results of this study in the rat preparation suggest a beneficial effect of "late" reperfusion on infarct expansion independent of myocardial salvage. If these results are confirmed in human beings, the period after myocardial infarction during which a patient can be considered for thrombolytic therapy or reperfusion by percutaneous transluminal coronary angioplasty could be greatly prolonged.
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